This application is based on Application No. 2001-209435, field in Japan on Jul. 10, 2001, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention generally relates to a fuel injection control device for an internal combustion engine. More particularly, the present invention relates to an improvement in a fuel injection control device for an internal combustion engine employing a structure in which the basic fuel injection volume can be determined based upon the intake pressure and a structure in which the basic fuel injection volume can be determined based on the throttle opening degree, together.
2. Description of Related Art
In the case of a normal two-wheeled vehicle, when an internal combustion engine (engine) is operated in a steady-state, the fuel injection is performed according to the basic fuel injection volume (hereinafter referred to as first basic fuel injection volume) based on the intake pressure and the engine speed. When the engine lies in a transient state, i.e. when the engine speed rapidly rises, however, the fuel injection is preferably performed according to the basic fuel injection volume (hereinafter referred to as second basic fuel injection volume) based on the throttle opening degree and the engine speed. Therefore, when the steady operation mode shifts to the transient operation mode, the fuel injection volume is usually switched between the first basic fuel injection volume and the second basic fuel injection volume according to a complement rate that is set in advance according to the engine speed and the throttle opening degree.
FIG. 4 is a block diagram showing the structure of a conventional fuel injection control device for an internal combustion engine. In FIG. 4, reference numeral 1 denotes a crank angle sensor for detecting the angle of a crank; 2, an intake pressure sensor for detecting the intake pressure of the air taken into an intake pipe; 3, a throttle sensor for detecting the throttle opening degree; 4, a variety of sensors for detecting data required for calculating an ignition timing.
Further, reference numeral 5 denotes a waveform shaping circuit for shaping a waveform of a detection signal S1 from the crank angle sensor 1; 6, a revolution speed calculating means for calculating an engine speed according to an output S5 from the waveform shaping circuit 5; 7, a first basic fuel injection volume calculating means for calculating a basic fuel injection volume according to the fuel volume calculated by using the engine speed and the intake pressure as parameters; 8, a second basic fuel injection volume calculating means for calculating a basic fuel injection volume according to a fuel volume calculated by using the engine speed and the throttle opening degree as parameters; 9, an injection volume switching section for switching the injection volume to the injection volume calculated by the first basic fuel injection calculating means or the injection volume calculated by the second basic fuel injection volume calculating means; 10, an ignition timing calculating means; 11, a CPU of the fuel injection control device, which includes the revolution speed calculating means 6, the first basic fuel injection volume calculating means 7, the second basic fuel injection volume calculating means 8, the injection volume switching section 9, and the ignition timing calculating means 10.
Reference numeral 12 denotes an injector drive circuit for causing injectors to inject fuel according to outputs from the injection volume calculating means 7 and 8 switched by the injection volume switching section 9, and reference numeral 13 denotes an ignition drive circuit for driving IG coils according to an output from the ignition timing calculating means.
Further, reference numerals 21 to 23 denote injectors, and reference numerals 31 to 33 denote IG coils.
FIG. 5 is a flow chart showing the operations for switching the injection volume between the injection volume calculated by the basic fuel injection volume calculating means 7 and the injection volume calculated by the basic fuel injection volume calculating means 8 in the fuel injection control device that is constructed in the above-mentioned manner.
Referring to FIG. 5, the throttle sensor 3 detects the throttle opening degree TH and outputs the detected value to the injection volume switching section 9 in the CPU 11 at a step 51.
At a step 52, the injection volume switching section 9 compares the throttle opening degree TH outputted from the throttle sensor 3 with a predetermined threshold. If the throttle opening degree TH is smaller than the threshold, the injection volume switching section 9 is switched so as to drive the injectors 21 to 23 according to the basic fuel injection volume that is calculated based on the engine speed and the intake pressure by the first basic fuel injection volume calculating means 7.
On the other hand, if the throttle opening degree TH is equal to or larger than the threshold, the injection volume switching section 9 is switched so as to drive the injectors 21 to 23 according to the basic fuel injection volume that is calculated based on the engine speed and the intake pressure signal by the second basic fuel injection volume calculating means 8.
As stated above, the conventional fuel injection control device for the internal combustion engine instantaneously switches the basic fuel injection volume between the two fuel injection volumes. For this reason, if the first basic fuel injection volume based on the intake pressure and the engine speed does not coincide with the second basic fuel injection volume based on the throttle opening degree and the engine speed when the basic fuel injection volume is switched, the calculated center of gravity fluctuates due to a variation in the engine speed or the load. This results in unstable feeling during the driving of a vehicle.
The present invention has been made to solve the above-mentioned problem, and it is therefore an object of the present invention to provide a fuel injection control device for an internal combustion engine that enables satisfactory combustion by switching the basic fuel injection volume between the basic fuel injection volume based on the intake pressure and the engine speed and the basic fuel injection volume based on the throttle opening degree and the engine speed in a preferable manner.
According to the present invention, there is provided a fuel injection control device for an internal combustion engine comprising: a crank angle sensor for detecting a revolution cycle of a crank shaft; an intake pressure sensor for detecting an intake pressure of air taken into an intake pipe; a throttle sensor for detecting a throttle opening degree of the intake pipe; rpm calculating means for calculating a rpm of the crank angle according to the revolution cycle of the crank shaft detected by the crank angle sensor; first basic fuel injection volume calculating means for calculating a first basic fuel injection volume by using the rpm and the intake pressure as parameters; second basic fuel injection volume calculating means for calculating a second basic fuel injection volume by using the rpm and the throttle opening degree as parameters; ratio calculating means for calculating a mixture ratio between the first basic fuel injection volume and the second basic fuel injection volume when a fuel injection volume is switched between the first basic fuel injection volume and the second basic fuel injection volume, and for gradually changing the mixture ratio at regular time intervals; and injector drive means for driving injectors so as to achieve an injection volume calculated by the ratio calculating means.
In the above-mentioned device, the ratio calculating means calculates the mixture ratio according to the operating conditions of the internal combustion engine.
In the above-mentioned device, the ratio calculating means regards the operating conditions of the internal combustion engine as at least a rpm of the internal combustion engine.
In the above-mentioned device, the ratio calculating means regards the operating conditions of the internal combustion engine as at least a temporal deviation in a rpm of the internal combustion engine.
In the above-mentioned device, the ratio calculating means regards the operating conditions of the internal combustion engine as at least information on a temperature of the internal combustion engine.
In the above-mentioned device, the ratio calculating means regards the operating conditions of the internal combustion engine as at least information on a gear position of a transmission in the internal combustion engine.
In the above-mentioned device, the ratio calculating means regards the operating conditions of the internal combustion engine as at least a throttle opening degree of the internal combustion engine.
In the above-mentioned device, the ratio calculating means regards the operating conditions of the internal combustion engine as at least a temporal deviation in a throttle opening degree of the internal combustion engine.